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  • PANGAEA  (1.067)
  • BioMed Central  (135)
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  • 1
    Publikationsdatum: 2018-08-10
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: PANGAEA Documentation , notRev
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  • 2
    Publikationsdatum: 2015-07-01
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: PANGAEA Documentation , notRev
    Format: application/pdf
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  • 3
    Publikationsdatum: 2018-08-10
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: PANGAEA Documentation , notRev
    Format: application/zip
    Format: application/zip
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  • 4
    Publikationsdatum: 2022-09-07
    Beschreibung: This study subdivides the Weddell Sea, Antarctica, into seafloor regions using multivariate statistical methods. These regions are categories used for comparing, contrasting and quantifying biogeochemical processes and biodiversity between ocean regions geographically but also regions under development within the scope of global change. The division obtained is characterized by the dominating components and interpreted in terms of ruling environmental conditions. The analysis uses 28 environmental variables for the sea surface, 25 variables for the seabed and 9 variables for the analysis between surface and bottom variables. The data were taken during the years 1983-2013. Some data were interpolated. The statistical errors of several interpolation methods (e.g. IDW, Indicator, Ordinary and Co-Kriging) with changing settings have been compared for the identification of the most reasonable method. The multivariate mathematical procedures used are regionalized classification via k means cluster analysis, canonical-correlation analysis and multidimensional scaling. Canonical-correlation analysis identifies the influencing factors in the different parts of the cove. Several methods for the identification of the optimum number of clusters have been tested. For the seabed 8 and 12 clusters were identified as reasonable numbers for clustering the Weddell Sea. For the sea surface the numbers 8 and 13 and for the top/bottom analysis 8 and 3 were identified, respectively. Additionally, the results of 20 clusters are presented for the three alternatives offering the first small scale environmental regionalization of the Weddell Sea. Especially the results of 12 clusters identify marine-influenced regions which can be clearly separated from those determined by the geological catchment area and the ones dominated by river discharge.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Other , NonPeerReviewed
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  • 5
    Publikationsdatum: 2022-09-07
    Beschreibung: This study subdivides the Potter Cove, King George Island, Antarctica, into seafloor regions using multivariate statistical methods. These regions are categories used for comparing, contrasting and quantifying biogeochemical processes and biodiversity between ocean regions geographically but also regions under development within the scope of global change. The division obtained is characterized by the dominating components and interpreted in terms of ruling environmental conditions. The analysis includes in total 42 different environmental variables, interpolated based on samples taken during Australian summer seasons 2010/2011 and 2011/2012. The statistical errors of several interpolation methods (e.g. IDW, Indicator, Ordinary and Co-Kriging) with changing settings have been compared and the most reasonable method has been applied. The multivariate mathematical procedures used are regionalized classification via k means cluster analysis, canonical-correlation analysis and multidimensional scaling. Canonical-correlation analysis identifies the influencing factors in the different parts of the cove. Several methods for the identification of the optimum number of clusters have been tested and 4, 7, 10 as well as 12 were identified as reasonable numbers for clustering the Potter Cove. Especially the results of 10 and 12 clusters identify marine-influenced regions which can be clearly separated from those determined by the geological catchment area and the ones dominated by river discharge.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Other , NonPeerReviewed
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  • 6
    Publikationsdatum: 2022-05-26
    Beschreibung: © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Microbiome 5 (2017): 18, doi:10.1186/s40168-017-0229-y.
    Beschreibung: We designed a two-phase study in order to propose a comprehensive and efficient method for DNA extraction from microbial cells present in corals and investigate if extraction method influences microbial community composition. During phase I, total DNA was extracted from seven coral species in a replicated experimental design using four different MO BIO Laboratories, Inc., DNA Isolation kits: PowerSoil®, PowerPlant® Pro, PowerBiofilm®, and UltraClean® Tissue & Cells (with three homogenization permutations). Technical performance of the treatments was evaluated using DNA yield and amplification efficiency of small subunit ribosomal RNA (SSU ribosomal RNA (rRNA)) genes. During phase II, potential extraction biases were examined via microbial community analysis of SSU rRNA gene sequences amplified from the most successful DNA extraction treatments. In phase I of the study, the PowerSoil® and PowerPlant® Pro extracts contained low DNA concentrations, amplified poorly, and were not investigated further. Extracts from PowerBiofilm® and UltraClean® Tissue and Cells permutations were further investigated in phase II, and analysis of sequences demonstrated that overall microbial community composition was dictated by coral species and not extraction treatment. Finer pairwise comparisons of sequences obtained from Orbicella faveolata, Orbicella annularis, and Acropora humilis corals revealed subtle differences in community composition between the treatments; PowerBiofilm®-associated sequences generally had higher microbial richness and the highest coverage of dominant microbial groups in comparison to the UltraClean® Tissue and Cells treatments, a result likely arising from using a combination of different beads during homogenization. Both the PowerBiofilm® and UltraClean® Tissue and Cells treatments are appropriate for large-scale analyses of coral microbiota. However, studies interested in detecting cryptic microbial members may benefit from using the PowerBiofilm® DNA treatment because of the likely enhanced lysis efficiency of microbial cells attributed to using a variety of beads during homogenization. Consideration of the methodology involved with microbial DNA extraction is particularly important for studies investigating complex host-associated microbiota.
    Beschreibung: This project was supported by NSF award OCE-1233612 to AA and NSF GRFP award to LW.
    Schlagwort(e): Coral microbiota ; DNA extraction ; Optimization ; SSU ribosomal RNA gene ; Amplicon sequencing
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 7
    Publikationsdatum: 2012-10-06
    Beschreibung: Background: Endopredict (EP) is a clinically validated multianalyte gene expression test to predict distant metastasis in ER-positive, HER2-negative breast cancer treated with endocrine therapy alone. The test is based on the combined analysis of 12 genes in formalin-fixed, paraffin-embedded (FFPE) tissue by reverse transcription-quantitative real-time PCR (qRT-PCR). Recently, it was shown that EP is feasible for reliable decentralized assessment of gene expression. The aim of this study was the analytical validation of the performance characteristics of the assay and its verification in a molecular-pathological routine laboratory. Methods: Gene expression values to calculate the EP score were assayed by one-step RT-qPCR using RNA from FFPE tumor tissue. Limit of blank, limit of detection, linear range, and PCR efficiency were assessed for each of the 12 PCR assays using serial samples dilutions. Different breast cancer samples were used to evaluate RNA input range, precision and inter-laboratory variability. Results: PCR assays were linear up to Cq values between 35.1 and 37.2. Amplification efficiencies ranged from 75% to 101%. The RNA input range without considerable change of the EP score was between 0.16 and 18.5 ng/ul. Analysis of precision (variation of day, day time, instrument, operator, reagent lots) resulted in a total noise (standard deviation) of 0.16 EP score units on a scale from 0 to 15. The major part of the total noise (SD 0.14) was caused by the replicate-to-replicate noise of the PCR assays (repeatability) and was not associated with different operating conditions (reproducibility). Performance characteristics established in the manufacturer's laboratory were verified in a routine molecular pathology laboratory. Comparison of 10 tumor samples analyzed in two different laboratories showed a Pearson coefficient of 0.995 and a mean deviation of 0.15 score units. Conclusions: The EP test showed reproducible performance characteristics with good precision and negligible laboratory-to-laboratory variation. This study provides further evidence that the EP test is suitable for decentralized testing in specialized molecular pathological laboratories instead of a reference laboratory. This is a unique feature and a technical advance in comparison with existing RNA-based prognostic multigene expression tests.
    Digitale ISSN: 1471-2407
    Thema: Medizin
    Publiziert von BioMed Central
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  • 8
    Publikationsdatum: 2012-10-02
    Beschreibung: Background: Gene duplications are a molecular mechanism potentially mediating generation of functional novelty. However, the probabilities of maintenance and functional divergence of duplicated genes are shaped by selective pressures acting on gene copies immediately after the duplication event. The ratio of non-synonymous to synonymous substitution rates in protein-coding sequences provides a means to investigate selective pressures based on genic sequences. Three molecular signatures can reveal early stages of functional divergence between gene copies: change in the level of purifying selection between paralogous genes, occurrence of positive selection, and transient relaxed purifying selection following gene duplication. We studied three pairs of genes that are known to be involved in an interaction with symbiotic bacteria and were recently duplicated in the history of the Medicago genus (Fabaceae). We sequenced two pairs of polygalacturonase genes (Pg11-Pg3 and Pg11a-Pg11c) and one pair of auxine transporter-like genes (Lax2-Lax4) in 17 species belonging to the Medicago genus, and sought for molecular signatures of differentiation between copies. Results: Selective histories revealed by these three signatures of molecular differentiation were found to be markedly different between each pair of paralogs. We found sites under positive selection in the Pg11 paralogs while Pg3 has mainly evolved under purifying selection. The most recent paralogs examined Pg11a and Pg11c, are both undergoing positive selection and might be acquiring new functions. Lax2 and Lax4 paralogs are both under strong purifying selection, but still underwent a temporary relaxation of purifying selection immediately after duplication. Conclusions: This study illustrates the variety of selective pressures undergone by duplicated genes and the effect of age of the duplication. We found that relaxation of selective constraints immediately after duplication might promote adaptive divergence.
    Digitale ISSN: 1471-2148
    Thema: Biologie
    Publiziert von BioMed Central
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  • 9
    Publikationsdatum: 2012-06-13
    Beschreibung: Background: The nuclear receptors (NRs) are an important class of transcription factors that are conservedacross animal phyla. Canonical NRs consist of a DNA-binding domain (DBD) and ligandbindingdomain (LBD). While most animals have 20-40 NRs, nematodes of the genusCaenorhabditis have experienced a spectacular proliferation and divergence of NR genes.The LBDs of evolutionarily-conserved Caenorhabditis NRs have diverged sharply from theirDrosophila and vertebrate orthologs, while the DBDs have been strongly conserved. TheNR2E family of NRs play critical roles in development, especially in the nervous system. Inthis study, we explore the phylogenetics and function of the NR2E family of Caenorhabditiselegans, using an in vivo assay to test LBD function. Results: Phylogenetic analysis reveals that the NR2E family of NRs consists of three broadlyconservedclades of orthologous NRs. In C. elegans, these clades are defined by nhr-67, fax-1and nhr-239. The vertebrate orthologs of nhr-67 and fax-1 are Tlx and PNR, respectively.While the nhr-239 clade includes orthologs in insects (Hr83), an echinoderm, and ahemichordate, the gene appears to have been lost from vertebrate lineages. The C. elegansand C. briggsae nhr-239 genes have an apparently-truncated and highly-diverged LBDregion. An additional C. elegans NR2E gene, nhr-111, appears to be a recently-evolvedparalog of fax-1; it is present in C. elegans, but not C. briggsae or other animals withcompletely-sequenced genomes. Analysis of the relatively unstudied nhr-111 and nhr-239genes demonstrates that they are both expressed--nhr-111 very broadly and nhr-239 in asmall subset of neurons. Analysis of the FAX-1 LBD in an in vivo assay revealed that it is notrequired for at least some developmental functions. Conclusions: Our analysis supports three conserved clades of NR2E receptors, only two of which arerepresented in vertebrates, indicating three ancestral NR2E genes in the urbilateria. The lackof a requirement for a FAX-1 LBD suggests that the relatively high level of sequencedivergence for Caenorhabditis LBDs reflects relaxed selection on the primary sequence asopposed to divergent positive selection. This observation is consistent with a model in whichdivergence of some Caenorhabditis LBDs is allowed, at least in part, by the absence of aligand requirement.
    Digitale ISSN: 1471-2148
    Thema: Biologie
    Publiziert von BioMed Central
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Publikationsdatum: 2013-08-14
    Beschreibung: Background: The taxonomic and phylogenetic relationships of the genus Phyllomedusa have been amply discussed. The marked morphological similarities among some species hamper the reliable identification of specimens and may often lead to their incorrect taxonomic classification on the sole basis of morphological traits. Phenotypic variation was observed among populations assigned to either P. azurea or P. hypochondrialis. In order to evaluate whether the variation observed in populations assigned to P. hypochondrialis is related to that in genotypes, a cytogenetic analysis was combined with phylogenetic inferences based on mitochondrial and nuclear sequences. Results: The inter- and intra-population variation in the external morphology observed among the specimens analyzed in the present study do not reflect the phylogenetic relationships among populations. A monophyletic clade was recovered, grouping all the specimens identified as P. hypochondrialis and specimens assigned P. azurea from Minas Gerais state. This clade is characterized by conserved chromosomal morphology and a common C-banding pattern. Extensive variation in the nucleolar organizing region (NOR) was observed among populations, with four distinct NOR positions being recognized in the karyotypes. Intra-population polymorphism of the additional rDNA clusters observed in specimens from Barreiras, Bahia state, also highlights the marked genomic instability of the rDNA in the genome of this group. Based on the topology obtained in the phylogenetic analyses, the re-evaluation of the taxonomic status of the specimens from the southernmost population known in Brazil is recommended. Conclusions: The results of this study support the need for a thorough revision of the phenotypic features used to discriminate P. azurea and P. hypochondrialis. The phylogenetic data presented here also contribute to an extension of the geographic range of P. hypochondrialis, which is known to occur in the Amazon basin and neighboring areas of the Cerrado savanna, where it may be sympatric with P. azurea, within contact zones. The misidentification of specimens may have led to inconsistencies in the original definition of the geographic range of P. azurea. The variability observed in the NOR of P. hypochondrialis reinforces the conclusion that these sites represent hotspots of rearrangement. Intraspecific variation in the location of these sites is the result of constant rearrangements that are not detected by classical cytogenetic methods or are traits of an ancestral, polymorphic karyotype, which would not be phylogenetically informative for this group.
    Digitale ISSN: 1471-2156
    Thema: Biologie
    Publiziert von BioMed Central
    Standort Signatur Einschränkungen Verfügbarkeit
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